rock tumbler

[Kratz] just turned into a rock hound and has a bunch of rocks from Montana that need tumbling. This requires a rock tumbler, and why build a rock tumbler when you can just rip apart an old inkjet printer? It’s one of those builds that document themselves, with the only other necessary parts being a Pizza Hut thermos from the 80s and a bunch of grit.

Boot a Raspberry Pi from a USB stick. You can’t actually do that. On every Raspberry Pi, there needs to be a boot partition on the SD card. However, there’s no limitation on where the OS resides, and [Jonathan] has all the steps to replicate this build spelled out.

Looking for one of those ‘router chipsets on a single board’? Here you go. It’s the NixCoreX1, and it’s pretty much a small WiFi router on a single board.

[Mowry] designed a synthesizer. This synth has four-voice polyphony, 12 waveforms, ADSR envelopes, a rudimentary sequencer, and fits inside an Altoids tin. The software is based on The Synth, but [Mowry] did come up with a pretty cool project here.

Don’t throw out that old printer! Not that you would, but even if you’ve already scavenged it for parts, you can use the shell and the rollers to make a rock/coin/what-have-you tumbler. If your printer is part scanner, it might end up looking as cool as [th3_jungle_inv3ntor]’s. You’ll have to laser-cut your own arachnid to supervise from above, though.

Somewhere between having an irreparable printer, being inspired by another tumbler, and the desire to make a mancala set for his sister-in-law, [th3_jungle_inv3ntor] was sufficiently motivated to get out his hacksaw and gut the printer. He used the main paper roller and its motor to do the tumblin’, and a smaller roller to help accommodate different jar sizes.

Aside from adding those sweet blue LEDs, he wired in a toggle switch, a speed control pot, and an LM317 to govern the tumbling rate. Unfortunately, the rocks in [th3_jungle_inv3ntor]’s town are too soft and crumbly, so he can’t make that mancala set after all. But hey, (almost) free stuff tumbler.

No dead printers lying around? If you have a drill and a vise, you could always make a tumbler that way, and nothing is compromised but the peaches jar.

[Chris] finds the average price of rock tumblers insulting. Almost as insulting, in fact, as prepackaged fruit salad made with Chinese peaches. While there may be little he can do about the peaches, he has given the finger to lapidary pricing by making his own tumbler on the very cheap.

Simply put, he drilled a hole in bottom of the peach vessel and then stuck a threaded rod through it. He held the rod in place with a nut and a washer. After securing the proper permits to source sand and water from his property, he put both in the jar along with some old nails that had paint and crud on them. [Chris] put the rod in the chuck of his drill and clamped the drill in his bench vise. Half an hour later, he had some nice, shiny nails. Make the jump to be amazed and entertained. If you prefer using balls, check out this homemade mill.

[Mike] enjoys doing all kinds of things with glass. He likes to melt it and fuse it into new things, so it’s perfectly understandable that he wanted to make his own glass. Doing so requires finely ground chemicals, so [Mike] put together this awesome homemade ball mill.

The design is wonderfully simple. The mill is powered by a robust 12VDC motor from a printer that he’s running from a variable power supply in order to fine tune the speed. [Mike] built a scrap wood platform and attached four casters for the drum to spin against. The drum is rotated by a round belt he had lying around from various other projects. [Mike] already had a couple of those blue containers, which formerly held abrasive grit for use in vibratory tumblers.

[Mike] had some trouble with the drum walking off the casters so he attached scrap piece of aluminum to form an end stop. All he had to buy for this project were the 5/8″ steel balls and the casters. The mill can also be used as a rock tumbler, though the bottle isn’t quite water tight as-is. He does not recommend this type of setup for milling gunpowder or other explosives, and neither do we.

Make the jump to see the mill in action and get the grand tour. If you need more tumbling power, use a dryer motor!